package com.mccree.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Arrays;

/**
 * Scattering:将数据写入到buffer时，可以采用buffer数组，依次写入【分散】
 * Gathering:从buffer读取到数据时，可以采用buffer数组,依次读
 */
public class ScatteringAndGatheringTest {
    public static void main(String[] args) throws IOException {
        //使用ServerSocketChannel和 SocketChannel网络
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        InetSocketAddress inetSocketAddress = new InetSocketAddress(7000);

        //绑定端口到socket，并启动
        serverSocketChannel.socket().bind(inetSocketAddress);

        //创建buffer数组
        ByteBuffer[] byteBuffers = new ByteBuffer[2];
        byteBuffers[0] = ByteBuffer.allocate(5);
        byteBuffers[1] = ByteBuffer.allocate(3);

        //等待客户端连接(telnet)
        SocketChannel socketChannel = serverSocketChannel.accept();

        int messageLength = 8;

        //读取数据
        while (true){
            int byteRead = 0;

            while (byteRead<messageLength){
                long l = socketChannel.read(byteBuffers);
                byteRead+=1;
                System.out.println("byteRead="+byteRead);
                //使用打印流看看当前的这个buffer的position和limit
                Arrays.stream(byteBuffers).map(buffer -> "position= "+buffer.position()+"limit = "+buffer.limit()).forEach(System.out::println);
            }
            //将所有的buffer进行flip
            Arrays.asList(byteBuffers).forEach(Buffer::flip);

            //将读取的数据显示到客户端
            long byteWrite = 0;
            while (byteWrite < messageLength){
                long l = socketChannel.write(byteBuffers);
                byteWrite+=1;
            }

            //将所有的buffer进行clear
            Arrays.asList(byteBuffers).forEach(Buffer::clear);

            System.out.println("byteRead="+byteRead+";byteWriter="+byteWrite+";messageLength="+messageLength);
        }
    }
}
